1. Field of the Invention
The present invention generally relates to an image recording apparatus such as an electronic camera for recording image data to a recording medium, and more particularly, a technology for securing unused capacity of the recording medium of the image recording apparatus.
2. Description of the Related Art
Generally in a case where an electronic camera apparatus such as a digital still camera is short of an unused capacity of a recording medium, image data that are recorded to the recording medium are erased so as to secure additional unused capacity of a recording medium. Erasing the image data can be performed by selecting individual pieces of the image data or selecting all of the image data. However, in a case of selecting individual pieces of the image data, the procedure is complicated. In a case of selecting all of the image data, although the procedure is not complicated, there is a disadvantage in that some image data desired to be retained cannot be stored.
In order to erase the image data that are recorded more efficiently and store the image data desired to be stored, the following technology is described in Japanese Laid-Open Patent Application, No. 2002-44601. That is, image data consisting of correlated image data such as image data taken consecutively, image data blanket-photographed, and image data panorama-photographed, are managed as a group. Furthermore, image data desired to be stored are protect-designated. Because of this, if image data belonging to a group are selected and ordered to be erased, other image data belonging to the same group, except image data that are protect-designated, are erased together.
Alternatively, there is another technology wherein image data that are recorded are not erased but the amount of the image data is reduced so that additional unused capacity of the recording medium is secured.
For example, Japanese Laid-Open Patent Application No. 8-9312 discloses a technology wherein selected image data are recompressed at a higher compression ratio, or a part of the image data is trimmed so that the amount of data is reduced. Japanese Laid-Open Patent Application No. 2001-320588 discloses a technology wherein a coded method having a multiple layer structure is applied and code data are reduced at a layer unit so that the amount of the image data is reduced. Japanese Laid-Open Patent Application No. 2001-231009 discloses image data that are recorded are recompressed and codes of a part of the code data are deleted so that the amount of the data is reduced and additional unused capacity corresponding to deleted pieces of recording image can be secured. In this technology, furthermore, the compression ratio of new image data is controlled so as to correspond to the additional unused capacity secured by reducing the amount of the data.
Japanese Patent No. 3229144 discloses a technology regarding control of the compression ratio of new image data wherein the control is automatically switched to an intermediate precision mode having a higher compression ratio when there is a lack of the unused capacity at a high precision mode.
Japanese Laid-Open Patent Application No. 2001-218062 discloses a technology of a system for managing a radiation image wherein the amount of data is reduced by a combination of deletion of a code in a non-interest area of image data that are stored, and recompression. In addition, Japanese Laid-Open Patent Application No. 2001-309138 discloses a technology of a copying machine in that color image data are transformed to black-and white image data so that the amount of the data is reduced.
A method wherein the amount of image data that is recorded is reduced so that additional unused capacity of the recording medium can be secured has an advantage as compared with a method for erasing image data in that image data desired to be stored are not erased completely. However, the selection of image data to have the recorded amount reduced depends on the user. The Japanese Patent Laid-Open Patent Application No. 2001-231009 merely discloses selecting image data having a maximum amount of recorded data.